Process of treating wood.



HAROLD M. NEWTON, OF MINNEAPOLIS, MINNESOTA.

rnocnss or TREATING woon. I i

We Drawing.

To all whom it may concern:

Be it known that I, HARoLu M. NEWTON, a citizen of the United States, and a resident of Minneapolis, in the county oftHennepin and State of Minnesota, have invented a certain new vand useful Process of Treating Wood, of which the following is a specification. r

My invention relates to processes for treating wood such as paving blocks, fence posts, railroad ties, timber and pilings with a preservative, for instance creosote, in liquid form.

Various processes have been suggested for treating wood with liquid creosote, includ ing the use of a suitable receptacle, usually called a treating cylinder, having a portion thereof, such as one end. removable whereby the wood may be placed within the hollow interior of the cylinder and the cylinder then closed, with means for inducing air or liquid pressure or a partial vacuum within til the cylinder, andmeansfor coilducting live steam'under pressure tothe interior thereof. The present process may be employed in connection withany suitable and well known apparatus-of the character described.

The chiefob ections to the use of creosoted wood at the present time are the initial presence on the surface and the subsequent exudation or bleeding therefrom 'ofcreosote and other substances, such as native pitches, gums, resins, etc., and the formation of a sticky, non-soluble, normally nonvolatile substance or compound thereon after the wood leaves the treating cylinder and frequently for several years after the wood so treated is placed in service. When wood, a paving block for instance, is treated in hitherto suggested ways, the preservative is distrib'uted quite unequally in the cells or voids throughout the wood, and the peripheral portions thereof are usually filled far more completely than are the interior portime. Furthermore, some of the constituduring the impregnating process, the finely divided carbonparticles held in suspension in the preserving oil and usually known as insoluble free carbon being filtered out on the wood. a

Specification of Letters Patent. Patented UM]. 31, 1916.

Application filed May 21, 1914:. Serial N0. 839,958. r

substances are also .carried to the surfacev when laid, thereby not only very sensibly lowering the melting point of the filler, but also forming a relatively much larger mass of objlectionable sticky substance. This action is more or less continuous, frequently.

for several vears,.throughout the summer months thereof. As these surface substances are carried by the feet of pedestrians into houses and stores,'the damage toproperty and the annoyance from this cause havebeen 'verv great.

The principal objects-of the presentin vention are to provide, in its broader aspect, a process for treating impregnated wood so as th cure the same of objectionable bleeding after it-leaves the treating cylinder; to remove superficial and other of the sticky compound referred. to and to prevent its formation and re-formation with the pitch used as a filler, as well as to remove the surface gums,oils, pitches,'resins, etc. and to prevent their subsequent exudation from A further object is to provide a complete process for impregnating wood whereby the wood may be substantially equallvcharged throughout with the desired quantity of preservative material, and in such manner that bleeding will not thereafter take place,

and .to provide a process for treating woodwhereby it will come from the treatingcylinder cleaned of gums, resins, pitches, creosote and the like substances and also be free of the sticky compound mentioned when the wood is put into use.

A still further object is to prevent the lowering of the meltiiig point of the pitchv filler used between paving blocks.

Where a preliminary treating process has been employed which has resulted in charging or impregnating the block or other form of wood with creosote or the like my process consists in additional steps to those already taken, and consists preferably first in applyact vacuum is created in the receptacle or treatsult thoroughly rally insensibly shading off toward the interior. The additional heat causes the absorbed creosote or other fluid preservative to expand and a wpart' thereofito exude fromthe outer portions of the wood. When the peripheral portions of the blockare thus heated the steam is turned off and a partial ing chamber, which vacuum is preferably not less than twenty inches of mercury, but may be higher, the vacuum being maintained until a portion of the peripheral creosote and the sticky substances are removed, the increased fluidity of the preservative at the higher temperature greatly facilitatingthis removal. As these peripheral portions were originally more completely charged than were the interior portions the result is a more uniform impregnation throughout the wood.

Various kinds of wood and various original treatments thereof will naturally require various periods of application of the live steam as well as of the vacuum; but the ap plication of live steam for any appreciable period and the subsequent provision of a vacuum for any appreciable period will rein advantage, and persons skilled in the art will readilyappreciatein any, instance for what periods the steaming or the vacuum operation should be employed to bring about the desideratum of an equable distribution of the creosote through vthe removal of the excess thereof from the surface and peripheral portions of the vgood.

ere wood is treated in accordance with my invention, substantially no more preservative will exude therefrom under the conditions to which it is subjected in actual serv: ice, that is to say, under atmospheric conditions. J

The preferred steps of my new process, where the Wood is treated completely in a series of operations resulting in a suitable charging of'the wood with a preservative and curingit of the bleeding. and other 0b jectionable properties mentioned, areas follows: The wood to be treated being considered within a treating cylinder the first step is to apply live steam to-the interior of the cylinder under a pressure of preferably about fifteen pounds per square inch,'which is preferablycontinued for asuflicient period to heat the wood to the center of defined each piece; secondly, placing the interior of the cylinder under vacuum, which may suitably be from say 20 to 27 inches, or higher, the vacuum being maintained preferably for a sufiicient period to remove substantially all pump applied, preferably slowly, and preferably of a low degree, say in the neighborhood of 100 pounds per square inch, the pressure being maintained until the desired amount of oil has been forced within the Wood. It is common practice to use considerable pressure upon the creosote, say 150 pounds per square inch and over, through a correspondingly shorter period, but I lfave found that such practice results in'choking the passages of, the peripheral portions of thepiece andinhibiting the free flow of the preservative to the center thereof. The fourth step consists in applying live steam the second time to the wood, it being understood, of course, that before doing sothe liquid creosote is withdrawn from the receptacle containing the wood. Thefifth and last step is causing a partial vacuum in the cyl-' inder. a v

The fourth and fifth steps just mentioned are the same as the first and second hereinabove described in connection with wood already treated with creosote, and these steps will require no further description v here. It may be stated, however, that where the process is carried through completely in a succession of closely following steps, as those vfrom one to five last hereinabove specified,

I have obtained excellent results by reverscation of the preferred order hereinabove set forth.

Within the meaning of the appended claims the first two steps of the preferred process for completely treating the wood, that is, live steaming and vacuum, consti tute a form of preparation of the wood for the reception. thereof of creosote; the first three steps constitute one; way, of charging or impregnating the wood and the last two steps constitute a suitable and preferred excess creosote to premanner of removin vent bleeding, and f or'cleaning the wood of creosote, gums, resins, pitches, sticky compounds and the like, and preventing the formation of the sticky compound withthe pitchy filler described. The several broadly paring the Wood, charging or impregnating the same, removing creosote, etc, from the outer or peripheral portions thereof, or

steps in some of the claims of pre cleaning substances therefrom are not respe'ctively limited to the specific steps in other claims set forth, as in its broad aspect I conceive that my discovery or invention resides both in taking Wood already treated and by additional treatment curing it of the objectionable properties hereinabove de-' scribed, and also, and more importantly, as a continuous seriesbf operations impregnating the wood with creosote or the like in such manner that thereafter it will be free of the objections named.

In its narrower aspects the invention or discovery resides in the specific steps ands in the union of specific and broadly defined steps as in some of the claims set forth.

It is also to be understood that the several steps of the process called for in the claims are to be considered as taken with the wood in a suitable receptacle or treating cylinder as hereinabove described.

It will readily be "appreciated that the present full-cell process is clearly distinguishable from what are known as empty cell processes in which the object is merely to coat or paint the surfaces of the cells throughout the wood without leaving them charged or filled with preservative material, the present process resulting in the substantial filling of the wood and with such quantity of the creosote removed from only'the peripheral portions of the wood as gives rise to the economic loss, bleeding and other objections hereinabove pointed out.

What I claim is:'

1. The process of preserving wood. which comprises impregnating wood by suitable treatment with a fluid preservative, and then removing some of said preservative from an outer layer only of said wood by applying additional heat and thereby causing exudation of preservative .from the wood, whereby subsequent bleeding is sub.- stantially prevented. i

2. The process of p comprises substantia 1y saturating wood with a fluid preservative, and then removing saidpreservative to a substantial extent from an outer layer only of said wood by application of additional heat and a partial vacuum. p

3. The process of preserving Wood which comprises impregnating wood by suitable treatment with a'fluid preservative, increasing the fluidity of said preservative in an outer layer only of the treated wood, and

withdrawing some of the preservative from said outer layer by means of a partial do s t ntially in an outer layer only of th vacuum.

4. The process of preserving wood which comprises impregnating wood by suitable treatment with a fluid preservative, then heating the treated wood externally to increase the fluidity of said preservative subeserving wood which 5. The process of treating wood with creosote or the like which comprises preparing the wood for the reception of creosote or the like in a suitable receptacle, applying the creosote or the like to the wood in such receptacle under pressure, and, after the wood is impregnated with preservative, applying to the'wood in said receptacle live steam unfder pressure to increase the'fluidity of the creosote only in the outer or peripheral portions of said Wood,-and causing a partial vacuum in said receptacle suflicient to withdraw some of the creosote from said outer portions ofthe wood.

6. The process of treating wood which comprises placing the wood within a suit-" able receptacle, applying live steam to the interior of said receptacle, producing a partial vacuum in said receptacle, then applying creosote or the like to the wood Within the receptacle under pressure, next drawing ofl the creosote or the like from the receptacleand applying live steam to the interior of said receptacle for a period of time sufiicient only to increase the fluidity of the preservative I in the outer portions of the wood, and then again producing a partial vacuum-therein to withdraw preservative from such outer portions.

7. The process" of treating wood pre viously impregnated with a preservative. capable of being rendered fluid which coniprises rendering the preservativesuitably fluid in an outer layer only of said wood, and then removing a part of the preserva tive from said layer, whereby subsequent bleeding issubstantially prevented. v

8. The process of treating'wood previously impregnated withcreosote or the like, to prevent bleeding, which comprises heating such impregnated wood in a suitable receptacle in such manner as to induce fluidity of the preservative in the peripheral portionsof the wood, and then causing a partial vacuum in such receptacle, wherelty some. of the creosote in said peripheral portions is withdrawn; v

9. The process of treating wood s viously impregnated with a preservative.

such ascreosote or the like, which comprises steaming such wood suficiently .to heat upsubstantially only an outer layer thereofv and thereby to render the preservative insaid layer suitably fluid ,and subjecting the steamed wood to the action, of a partial vacuum for a vperiod of time suflicient-to remove some of'said preservative from said outer layer.

-'10. The process of treating wood, impregnated with creosote or the like, to prevent bleeding and to remove gums, pitches and the like therefrom, which comprises heatpreservative in a suitable treating recep ing .in a suitable receptacle the peripheral portions only of thewood so impregnated, whereby the creosote or the like in such pee-r ripheral portions is rendered more 'fiuid,' and causing a partial vacuum in; such receptacle and thereby withdrawing preservative from such peripheral portionsp' 11. The process of preserving wood which 7 comprisessubstantially filling the cells andvoids of the wood throughout with a' fluid tacle, and then applying live steam to said wood for a period of time suflicient to expand'and drive out a portion of the-pre'.

servative from the outer layersof the wood,

whereby substantially no more preservative will exude therefrom under atmospheric.

" within said receptacle.

13., The process of treating wood, which comprises placing the wood in a closed re= ceptacle, applying-live steam to the wood, producinga partial vacuum in said receptacle; then applying creosote orthe like to the wood under pressure, next drawing 01%." the surplus creosote or the like from the re- I ceptacle, andthen increasingthe temperature inside the receptacle tofan extent sufinaoaoee cient to cause expansion of the'preservative I and exudation thereof to a substantial ex- "tent from the outer portions of the wood whereby subsequent bleeding is substan-v stantially prevented. r

I, 14:. The process of preserving wood which comprises subjecting wood to a full cell treatment with creosote or the like preservative, then applying heat to said wood ;.to cause expansion of the preservative in an outer layer of the wood and exudation of apart of the preservative therefrom, and re 7 moving the exuded preservative.-

15. In a full cell process of presrvin substantially non-bleeding, which comprises applying additional heat to the substantially saturated wood and thereby causing exudation of a suficient quantity of preser-.

vative from the outer portions thereof to substantially prevent the wood from bleeding suhsequently under conditions of prac- G0 I timl use. a

16. A wood paving block impregnated suhstantially through with creosote or the like preservative according to a full cell treatment, the peripheral portions of said hlock having such a degree of impregnation per unit of volume that under atmospheric conditions said block is substantially free from exudation or the preservative.

HARULD li L NEWTON Witnesses:

T. D.- BUTLER, Lerner Jenna.

to I wood with creosote or'the like preservative,

the final treatment for rendering the wood 

